Min ladder test temp for TAC/69gr

[1168]

Word Up! Primers can completely change the pressure curve of a load with all things else held constant. I really have never had luck with the ladder test stuff.

If I were... (and I usually have to be)... worried about temp swings, I'd work a load that had 100-200 FPS upside cushion from a 5.56 load with crimped primers. For example, when I used to shoot W748 and 55 gr fmj. I'd shoot for 3100 fps out of a 20" gun to leave me some margin for error/hotter temps.

Exactly.

With some manuals, there’s a bit of a cushion because the max load was worked up in a minimum dimension .223 Rem chamber, and our ARs don’t usually have those. Of course, we can’t rely on that because: a)some powders seem to get squirelley near max b) some manuals are actually quite hot, like Western’s 5.56 section* c) lot-to-lot variation and d) we don’t really know how much the pressure will change with temp, or what our average/max pressure is, as handloaders, because we can only measure pressure indirectly, and likely have not even done that.

There can be benefits to using slower or predictable powders, or just giving yourself some margin, and they don’t always show up on paper.

*I did a workup with Tac and got flat primers and spicy recoil well before book max, using Hornady 55 fmj.

[joedirt199]

I am settling around 24.2-24.3 with my 68 and 69 loads. I load them short 2.23", I was just starting to get decent ES's in the 20s around 24.2.

[223to45]

Exactly.



*I did a workup with Tac and got flat primers and spicy recoil well before book max, using Hornady 55 fmj.

Well, depending on the data source, 25gr of Tac is toward the upper range in one book, and toward the lower range in another.

Just started playing with Tac, so not sure yet which one is more correct

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